CS 1110/1111

The Case for Computer Science

CS 1110/1111 – Introduction to Programming

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The Course Goals

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• To teach the skill of programming• To teach the art of computer science

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Look around…• Where do you see computing at work in the

world?

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A question• First, what is an operating system?• Second, how many operating systems have you

used?

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Really? How many?• Think of all the devices that contain operating

systems of some kind…

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So I ask again…• Where do you see computing at work in the

world?• Heck, look just in this room! In your dorm

room / apartment!

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A system of interest• SIS• What's wrong with SIS?

– (remember – we only have so much time in this class today…)

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Cri-SIS• Thoughts?

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Okay, that was cathartic• Now let's back up for a minute• Why do we have SIS?

– What's the underlying “problem” it's trying to solve?

– Is this fundamentally a “computer science” problem? If so, what's the problem? If not, what discipline does it come from?

• Activity: A Cri-SIS– Groups of 3 or 4; Answers these questions

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A Big, Scary Computer Science Word• “Algorithm”• Definition?

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Algorithms – What do they mean?• A step-by-step process for solving a problem• A recipe!

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Well… what's a program?• A program is an implementation of an

algorithm that a computer can understand

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The Challenge

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Electricity Functionality

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Abstraction• Split up the problem into

several layers• Each intermediate layer will:

– Use what its lower layer provides to do something

– Hide the characteristics of the layers below it to the layer above

• The lower layers are in hardware and the higher layers in software

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Get electricity into the computer

Provide the required functionality to the user

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Let's Pause for a Moment• What is a programming language?

– A language that allows you to express computations performed by a “machine”.

– But, a machine has several layers.• Each layer has its own programming language!

– The language allows the functionality provided by a layer to be used without knowing how it is implemented (Abstraction)

• What does a language do?– Provide representations for data– Define operations on the data

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Assembly Language(we're now in software land)

• Data: A collection of logical bits

• Operations: ADD, SUB, MULTIPLY,… (instructions)

• A sequence of instructions that perform a computation form a program.

• A program uses data that is stored in memory.

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.datahellostring: .ascii "Hello “

.asciiz "World!\n"

.textmain: la $a0, hellostring li $v0, 4 syscall

li $v0, 10 syscall

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High-Level Language (HLL)• Uses data

representations and constructs that are much easier to use to convert the high-level computation steps (algorithm) to a computer program to achieve the desired functionality.

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